U.S. patent application number 13/574471 was filed with the patent office on 2012-11-15 for positively charged ink composition.
This patent application is currently assigned to Hewlett-Packard Indigo B.V.. Invention is credited to Gil Bar-Haim, Yigal Berson, Yaron Grinwald.
Application Number | 20120287180 13/574471 |
Document ID | / |
Family ID | 42941906 |
Filed Date | 2012-11-15 |
United States Patent
Application |
20120287180 |
Kind Code |
A1 |
Grinwald; Yaron ; et
al. |
November 15, 2012 |
POSITIVELY CHARGED INK COMPOSITION
Abstract
Positively charged ink compositions, its use and method of
making the same are disclosed. A disclosed example of the
positively charged ink compositions includes a combination of a
carrier liquid, basic pigment-loaded resin particles, a charge
director and an acidic charge adjuvant.
Inventors: |
Grinwald; Yaron; (Melter,
IL) ; Bar-Haim; Gil; (Holon, IL) ; Berson;
Yigal; (Lod, IL) |
Assignee: |
Hewlett-Packard Indigo B.V.
Maastricht
NL
|
Family ID: |
42941906 |
Appl. No.: |
13/574471 |
Filed: |
March 9, 2010 |
PCT Filed: |
March 9, 2010 |
PCT NO: |
PCT/EP10/52988 |
371 Date: |
July 20, 2012 |
Current U.S.
Class: |
345/690 ;
252/500; 252/519.21; 359/296 |
Current CPC
Class: |
C09D 11/38 20130101;
G02F 2001/1678 20130101; C09D 11/36 20130101; C09D 11/033 20130101;
C09D 11/106 20130101; C09D 11/322 20130101 |
Class at
Publication: |
345/690 ;
252/500; 252/519.21; 359/296 |
International
Class: |
H01B 1/12 20060101
H01B001/12; G02F 1/167 20060101 G02F001/167; G09G 5/10 20060101
G09G005/10 |
Claims
1. A positively charged ink comprising a combination of: a. a
carrier liquid, b. basic pigment-loaded resin particles, c. a
charge director, d. and an acidic charge adjuvant.
2. The positively charged ink according to claim 1 wherein the
resin of the particle is a homopolymer or a copolymer of polyvinyl
pyrrolidone.
3. The positively charged ink according to claim 1 wherein the
resin of the particle is a vinyl pyrrolidone/triacontene
copolymer.
4. The positively charged ink according to claim 1 wherein the
basic pigment-loaded resin particles exhibit an average particle
size of less than 1.0 micron and contain a resin that exhibits a
molecular weight of 500 to 20,000.
5. The positively charged ink according to claim 1 wherein the
charge director is an organic multi-valent metal salt.
6. The positively charged ink according to claim 1 wherein the
charge director is zirconium octoate or zirconium 2-ethyl
hexanoate.
7. The positively charged ink according to claim 1 wherein the
charge adjuvant has the formula X.sub.n(R.sup.a)(R.sup.b)(COOH) or
X.sub.n(R.sup.a)(R.sup.b) wherein X is F, Cl, Br, NO.sub.2 or CN;
R.sup.a is a substituted or unsubstituted alkyl group; R.sup.b is
Sb, P, Ti, Sn, B, Al, Zn, a phenol or a benzene group and wherein n
is 1, 2, 3, 4 or 5.
8. The positively charged ink according to claim 1 wherein the
charge adjuvant is present in an amount representing from about 1
to about 5 weight percent of the total amount of solids present in
the ink composition.
9. The positively charged ink according to claim 1 wherein the
charge adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid or
4-(2,4-dichlorophenoxy)butyric acid.
10. The positively charged ink according to claim 1 wherein the
charge adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid and is
present in an amount representing from about 3 to about 5 weight
percent of the total amount of solids present in the ink
composition.
11. The positively charged ink according to claim 1 wherein the
resin is a vinyl pyrrolidone/triacontene copolymer and the charge
adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid.
12. The positively charged ink according to claim 1 wherein the
resin is a vinyl pyrrolidone/triacontene copolymer, the charge
adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid and the charge
director is zirconium 2-ethyl hexanoate.
13. A method of making a positively charged ink comprising: a)
grinding a carrier liquid, a basic resin and a pigment to form a
slurry, wherein the resin is a vinyl pyrrolidone/triacontene
copolymer; b) mixing a charge adjuvant and a charge director in the
slurry after grinding, wherein the charge adjuvant is
2-(4-chlorophenyl)-3-methylbutyric acid or
4-(2,4-dichlorophenoxy)butyric acid; c) and forming the ink.
14. An electronic display comprising: a) a pixel; b) an electrode
in the pixel; c) and an ink in the pixel, wherein the ink is a
positively charged ink comprising a combination of a carrier
liquid, basic pigment-loaded resin particles, a charge director,
and an acidic charge adjuvant.
15. An image displaying method comprising: a) providing an
electronic display including a pixel allowing visible light to
enter and exit the pixel, an electrode in the pixel, and electronic
ink in the pixel, wherein the ink is a positively charged ink
comprising a combination of a carrier liquid; basic pigment-loaded
resin particles; a charge director and an acidic charge adjuvant;
b) applying an electrical signal to the pixel using the electrode
and compacting the charged particles using the electrical signal;
c) and changing the electrical signal and dispersing the charged
particles across the pixel.
Description
BACKGROUND
[0001] Ink compositions containing charged particles are used in a
wide variety of applications such as electro-conductive additives
to plastics, toners in electrophotography printing, pigmented ink,
electrophoretic display as well as many other applications. Such
inks are often referred to as electronic inks Such electronic inks
traditionally include charged particles, such as colorant
particles, in order to help the particles to respond to electric
field.
[0002] Currently, charged particles that are used in electronic ink
materials or in electrophoretic display materials, as examples, are
mostly negatively charged. This unidirectional charging mechanism
often limits the design of devices. Indeed, as an example, when
particles are pigments, the negative charge limits device
architecture to have stacked layers in order to accommodate
multiple colors. As an example, such architecture often results in
that most of the light incident to the display is scattered by the
top layers and, therefore, insufficient light reaches the bottom
layer which lead thus to performance issues such as low optical
density.
[0003] Many methods have been proposed to produce such positively
charged inks However, investigations continue into developing
positively charged inks
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Exemplary embodiments are described below with reference to
the attached figures, which show experimental results that
illustrate the effect of exemplary embodiments of the
disclosure.
[0005] FIGS. 1 and 2 are comparative graphs representing measured
particle conductivities of example ink compositions, in relation
with resins and charge adjuvant natures.
[0006] FIG. 3A is a graph representing measured particle
conductivities of example ink compositions, in relation with charge
director concentration, at different kinetic states.
[0007] FIG. 3B is a graph representing direct current conductivity
(DC) of example ink compositions, in relation with charge director
concentration, at different kinetic states.
[0008] FIG. 4 is a graph representing measured particle
conductivities of example ink compositions, in relation with charge
director concentration, at different charge adjuvant
concentrations.
[0009] FIG. 5 is a graph representing measured conductivities (PC,
HFC, LFC, Dc and PC) of example ink compositions, in relation with
dispersant concentrations.
[0010] FIG. 6 is a graph representing measured conductivities (PC,
HFC, LFC, Dc and PC) for example ink composition containing black
pigment during 48 hours.
DETAILED DESCRIPTION
[0011] Embodiments of the present disclosure will employ, unless
otherwise indicated, techniques of synthetic organic chemistry, ink
chemistry, electrochemistry, chemistry of conducting compounds,
media chemistry, printing chemistry, and the like, that are within
the skill of the art. Such techniques are explained fully in the
literature. The following examples are put forth to provide those
of ordinary skill in the art with a complete disclosure and
description of how to perform the methods and use the compositions
disclosed and claimed herein. Efforts have been made to ensure
accuracy with respect to numbers (e.g., amounts, temperature, etc.)
but some errors and deviations should be accounted for. Unless
indicated otherwise, temperature is in .degree. C., and pressure is
at or near atmospheric. Standard temperature and pressure are
defined as 20.degree. C. and 1 atmosphere. Unless otherwise
indicated, the viscosity is measured at a shear rate of 11 l/sec,
is expressed in cps, and is measured at a temperature of 25.degree.
C.
[0012] Before embodiments of the present disclosure are described
in detail, it is to be understood that, unless otherwise indicated,
the present disclosure is not limited to particular materials, and
processes disclosed herein. It is also to be understood that the
terminology used herein is for purposes of describing particular
embodiments only, and is not intended to be limiting, as the scope
of the present invention will be defined only by the claims and
equivalents thereof. In the present specification, and in the
claims, the following terminology will be used: the singular forms
"a", "an" and "the" include plural referents unless the context
clearly dictates otherwise. Thus, for example, reference to "a
support" includes a plurality of supports. The terms "about" and
"approximately," when referring to a numerical value or range is
intended to encompass the values resulting from experimental error
that can occur when taking measurements. Concentrations, amounts,
and other numerical data may be presented herein in a range format.
It is to be understood that such range format is used merely for
convenience and brevity and should be interpreted flexibly to
include not only the numerical values explicitly recited as the
limits of the range, but also to include all the individual
numerical values or sub-ranges encompassed within that range as if
each numerical value and sub-range is explicitly recited. For
example, a weight range of about 1 weight percentage (wt %) to
about 20 weight percentage (wt %) should be interpreted to include
not only the explicitly recited concentration limits of 1 wt % to
approximately 20 wt %, but also to include individual
concentrations such as 2 wt %, 3 wt %, 4 wt %, and sub-ranges such
as 5 wt % to 15 wt %, 10 wt % to 20 wt %, etc.
[0013] In some embodiments, the present disclosure refers to an ink
which is positively charged and which contains a carrier liquid,
basic pigment-loaded resin particles, a charge director and an
acidic charge adjuvant. As an example, the ink is an electronic
ink. As electronic ink, it is meant herein a low dielectric fluid
that contains charged particles such as, for example, a colorant or
a pigment encapsulated by a polymer capable of adsorbing a charge.
Such particles are in suspension in a liquid carrier. Some
electronic inks may be referred to as electrophoretic or low
dielectric inks where the charged particles may be moved with a
Coulombic force exerted on the particles by an applied electrical
signal.
[0014] In some embodiments, the present disclosure refers to method
for making such ink. In some other embodiments, the present
disclosure refers to uses of this ink in electronic display. In
some embodiments, the present disclosure refers to electronic
display containing such ink.
[0015] In some examples, it has likewise been observed that acidic
charge adjuvant, when added to positively charged ink composition,
improves effectiveness of a charge director containing such ink
composition.
[0016] The inks disclosed herein are suitable for use in a variety
of applications, including display applications, electronic skins,
blanket jetting applications, digital printing applications, ion
beam printing applications, or other printing applications.
[0017] In some embodiments, the electronic ink of the present
disclosure includes basic, pigment-loaded, resin particles. As
"pigment-loaded resin particle", it is meant herein particle
including at least a pigment and a resin polymer, the pigment being
embedded in a resin polymer. In some examples, the ink includes a
basic resin. As examples, the resin may be a thermoplastic resin
exhibiting a melting point of greater than 50.degree. C., including
greater than 90.degree. C. As another example, the resin may be a
basic wax resin. As "basic", it is meant herein that the resin has
the capacity of attracting protons (H.sup.+).
[0018] In some embodiments, the resin includes polymers such as
polyamines, polyamides, and potentially others polymers. In some
examples, the resin is a homopolymer or a copolymer of polyvinyl
pyrrolidone. In some other examples, the resin is a copolymer of
polyvinyl pyrrolidone. Examples of monomers polymerized with vinyl
pyrrolidone in order to form the polyvinyl pyrrolidone copolymers
include, but are not limited to, alkylmethacrylates-acrylates such
as butylmethacrylates, methylmethacrylates and the like.
Illustrative examples of polyvinyl pyrrolidones polymers include,
for example, styrene/butylmethacrylate/vinyl pyrrolidone
terpolymers, vinyl pyrrolidone/vinyl acetate copolymers, vinyl
pyrrolidone homopolymers, and the like. In some other embodiments,
the resin is a vinyl pyrrolidone/triacontene copolymer (a copolymer
of vinylpyrrolidone grafted with triacontene). In some more
specific embodiments, the resin is 2-pyrrolidinone 1-ethenyl
triacontene polymer.
[0019] In some examples, the resin is a polyvinyl pyridine polymer
or copolymer such as polyvinyl pyridine co-styrene or polyvinyl
pyridine co-butyl methacrylate. In some other embodiments, the
resin is an amino terminated polyacrylates such as poly(t-butyl
amino ethyl methacrylate) or poly(dimethyl amino ethyl
methacrylate). In some other examples, the resin is a polymer or
copolymer selected from the group consisting of polyethylene imine;
polyethylene oxide diamine terminated; polypropylene oxide,
monoamine or di-amine terminated; polyamide; polydimethyl siloxane
diamino propyl terminated; ethylene/butylene copolymer mono and
dihydroxy terminated; hydroxyl ethyl cellulose.
[0020] Exemplary embodiments of the resin of the present disclosure
include Antaron.RTM.WP-660 wax resin, a copolymer available from
International Specialty Products and Alcyn.RTM.575 wax resin, a
copolymer available from Honeywell Inc.
[0021] In some examples, the basic resin may exhibit a molecular
weight ranging from 500 to 20,000. In other examples, the basic
resin has a molecular weight ranging from 1,000 to 5,000; in yet
other examples, the basic resin has a molecular weight ranging from
3,000 to 4,500.
[0022] As an example, in the ink composition, the resins are in the
form of particles. In some embodiments, the resin particles include
pigments that are loaded on the resin particles. In some other
embodiments, the pigment-loaded resin particles exhibit an average
particle size of less than 3.0 micron. In yet some other
embodiments, the pigment-loaded resin particles exhibit an average
particle size of less than 2.0 micron; and in yet some other
embodiments, the pigment-loaded resin particles exhibit an average
particle size if less than 1.0 micron. In some examples, the
pigment-loaded resin particles exhibit an average particle of size
less than 1.0 micron and contain a resin that exhibits a molecular
weight of 500 to 20,000.
[0023] In some examples, the pigment loading may represent from
about 1 to about 99 weight percent (wt %) of the total amount of
solids present in the ink composition, i.e. wt % of total weight of
non volatile substances; in some other examples, the pigment
loading may represent from about 10 to about 90 wt %, or even from
about 20 to about 75 wt % of the total amount of solids present in
the ink composition. In yet other embodiments, the pigment
represent from about 30 wt % to about 65 wt % of total weight of
non volatile substances present in the ink composition.
[0024] Illustrative examples of potentially suitable pigments are
Cabot Mogul L.RTM. (black), Monastral Blue G.RTM. (C.I. Pigment
Blue 15 C.I. No. 74160), Quindo.RTM. Magenta (Pigment Red 122),
Indo.RTM. Brilliant Scarlet Toner (Pigment Red 123, C.I. No.
71145), Dalamar.RTM. Yellow (Pigment Yellow 74, C.I. No. 11741),
blue pigment BT-383D (DuPont), yellow pigment YT-717D (DuPont), red
pigment RT-455D (DuPont) and blue pigment Helioecht.RTM. Blue GO
(Bayer). Another illustrative example of the pigment includes
Paliotol.RTM. yellow D1155 available from BASF.
[0025] In some examples, the resins involves the property of being
compatible with a cyan pigment, a magenta pigment, a yellow
pigment, a black pigment, and combinations thereof. Such
compatibility allows development of CMYK color systems derivable
from the same resin/charge director composition. In addition, such
compatibility allows tuning or adjustment of the color gamut since
the resin exhibits compatibility with combinations of pigments.
Individual particles may include more than one of the CMYK pigments
and/or other base or secondary pigments and may exhibit any color
from various pigment combinations, such as, any color within the
available Pantone spot color space. Thus, in some embodiments, the
pigments are cyan pigments, magenta pigments, yellow pigments,
black pigments or any combinations thereof.
[0026] The combination of resin particles and pigments may be
contrasted with particles produced from in situ encapsulation
during polymerization or from other similar known techniques. In
the combination, the starting materials include solid resin
particles and pigments, and processing yields particles of the
solid resin loaded with pigment. Known in situ particles result
from polymerization of precursor chemicals in solution in
conjunction with encapsulation of pigment also in solution. No
combination of resin particles and pigment occurs during known in
situ encapsulation since no resin particles exist in the precursor
solution. Instead, the only combining that occurs involves
polymerization precursors and pigment.
[0027] In some examples, the resin may represent from about 1 to
about 99 weight percent (wt %) of the total amount of solids
present in the ink composition, i.e. wt % of total weight of non
volatile substances (NVS). In some other examples, resin may
represent from about 25 to about 80 wt % of the total amount of
solids present in the ink composition. In yet some other examples,
resin may represent from about 35 to about 70 wt % of the total
amount of solids present in the ink composition.
[0028] In some embodiments, the charge adjuvant is an acidic charge
adjuvant. In some examples, the charge adjuvant may be chemically
bond to the basic pigment-loaded resin particles. As used herein,
the term "charge adjuvant" is used to designate an additive added
to inks that allows the binding and/or activation of the charge
control agent/charge director. Without being linked by any theory,
it is believed that the acid charge adjuvant interferes with the
basic resin and lead to obtain a higher positive particle
conductivity of electrophoretic particles. As "acid", is it means
herein a Lewis acid or an organo-Lewis acid.
[0029] In some embodiments, the charge adjuvant is a charge
adjuvant having the formula X.sub.n(R.sup.a)(R.sup.b) or
X.sub.n(R.sup.a)( R.sup.b)(COOH) wherein X is F, Cl, Br, NO.sub.2
or CN; R.sup.a is a substituted or unsubstituted alkyl group;
R.sup.b is Sb, P, Ti, Sn, B, Al, Zn, a phenol or a benzene group
and wherein n is 1, 2, 3, 4 or 5.
[0030] In some embodiments, the charge adjuvant is a charge
adjuvant having the formula X.sub.n(R.sup.a)(R.sup.b)(COOH) wherein
X is F, Cl, Br, NO.sub.2 or CN; R.sup.a is a substituted or
unsubstituted alkyl group; R.sup.b is Sb, P, Ti, Sn, B, Al, Zn, a
phenol or a benzene group and wherein n is 1, 2, 3, 4 or 5.
[0031] In some other embodiments, the charge adjuvant has the
formula X.sub.n(R.sup.a)(R.sup.b)(COOH), wherein X is Cl; R.sup.a
is a substituted or unsubstituted alkyl group having from 3, 4 or 5
carbon atoms, R.sup.b is a benzene or a phenol group and n is 1 or
2. In some other embodiments, the charge adjuvant has the formula
X.sub.n(R.sup.a)(R.sup.b)(COOH), wherein X is Cl; R.sup.a is an
alkyl group having 5 carbon atoms; R.sup.b is a benzene group and n
is 1. In some embodiments, the charge adjuvant has the formula
X.sub.n(R.sup.a)(R.sup.b)(COOH), wherein X is Cl; R.sup.a is an
alkyl group having 4 carbon atoms; R.sup.b is a phenol group and n
is 2.
[0032] In some examples, R is an alkyl group. The term "alkyl" as
used herein means a branched, unbranched or cyclic saturated
hydrocarbon group, which typically, although not necessarily,
contains from 1 to about 20 carbon atoms, or 1 to about 15 carbon
atoms, or 1 to about 10 carbon atoms for example. Alkyls include,
but are not limited to, methyl, ethyl, n-propyl, isopropyl,
n-butyl, isobutyl, t-butyl, octyl, and decyl, for example, as well
as cycloalkyl groups such as cyclopentyl, and cyclohexyl, for
example. In some other embodiments, R is a lower alkyl group. The
term "lower alkyl" means an alkyl group having from 1 to 8 carbon
atoms. In some other example, R is a substituted alkyl group or a
heteroalkyl alkyl group. As used herein, the term "substituted
alkyl" means an alkyl substituted with one or more substituent
groups. The term "heteroalkyl" means an alkyl in which at least one
carbon atom is replaced with a heteroatom.
[0033] In some embodiments, the charge adjuvant is a chloro-phenyl
carboxylic acid. In some embodiments, the charge adjuvant is
2-(4-chlorophenyl)-3-methylbutyric acid or
4-(2,4-dichlorophenoxy)butyric acid. In some other embodiments, the
charge adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid.
[0034] In some examples, the charge adjuvant represents from about
0.05 to about 8 weight percent (wt %) of the total amount of solids
present in the ink composition, i.e. wt % of total weight of non
volatile substances (NVS). In some other examples, the charge
adjuvant may represent from about 0.125 to about 6 wt % of the
total amount of solids present in the ink composition. In some
other examples, the charge adjuvant is present in an amount
representing from about 1 to about 5 wt % of the total amount of
solids present in the ink composition. In yet some other examples,
the charge adjuvant is present in an amount representing about 4 wt
% of the total amount of solids present in the ink composition. In
exemplary embodiments of the present disclosure, the charge
adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid and is present
in an amount representing from about 3 to about 5 weight percent of
the total amount of solids present in the ink composition.
[0035] In some embodiments, the ink of the present disclosure
includes charge directors. Charge directors refer herein to
components that induce and/or increase charge on particles. In some
examples, the charge director, or charge control agent or charging
agent, is physically associated to resin particles. In some other
examples, the charge director is a positive charging agent. In some
other examples, the charge director is a positive charging agent
having the form of a positive organic charged micelle when used in
non-polar solvents, such as hydrocarbon solvents. By way of
example, the charge director may form a micelle structure
physically associated (by hydrophobic bonding), but not chemically
associated, with resin particles to provide at least part of the
particle charge. Hydrophobic bonding or, more appropriately,
hydrophobic interaction represents a well-known phenomenon that
occurs in micellular structures. In nonpolar solvents, hydrophilic
heads of amphiphilic molecules orient the molecules to assemble the
hydrophilic heads together inside the micelle with hydrophobic
tails assembled outside at the micelle surface in what is called
reverse micelle. Thus, without being linked by any theory, the
charge director forms a micelle structure physically associated by
hydrophobic bonding with the resin particles to provide at least
part of the particle charge. In some examples, the charge director
forms reverse micelle.
[0036] In some embodiments, the charge director is a positive
charge director. The charge director gives thus positively charge
to resin particles. In some examples, the charge director has thus
the benefit of providing a positive charge to the resin particles,
resulting thus in basic pigment-loaded resin particles which are
positively charged. The charged particles will thus be switchable
by an electric field. In addition, this positive charging system
provides the possibility to charge any kind of color and/or many
additives, with no regard to the kind of pigment or additives
used.
[0037] In some embodiments, the charge director is an organic
multi-valent metal salt. Said organic salt is dissolved in the
liquid carrier and is soluble in the carrier liquid at room
temperature.
[0038] Examples of charge directors include organic acid metal
salts consisting of polyvalent metal ions and organic anions as the
counterion. Non-limiting examples of suitable metal ions include
Ba(II), Ca(II), Mn(II), Zn(II), Zr(IV), Cu(II), Al(III), Cr(III),
Fe(II), Fe(III), Sb(III), Bi(III), Co(II), La(III), Pb(II), Mg(II),
Mo(III), Ni(II), Ag(I), Sr(II), Sn(IV), V(V), Y(III), Ta(V), and
Ti(IV). Non-limiting examples of suitable organic anions include
carboxylates or sulfonates derived from aliphatic or aromatic
carboxylic or sulfonic acids.
[0039] In some embodiments, charge directors may be selected from
the group consisting of manganese naphthenate, manganese octoate,
zirconium octoate and cobalt octoate, iron naphthenate, magnesium
octoate, titanium(IV)2-ethyl-1,3 hexanedio late,
titanium(IV)-2-ethylhexyloxide, zirconium(IV)-ter-butoxide,
tantalum(V)-butoxide, poly-oxo-aluminum tristearate, zinc
naphthenate, barium distearate and calcium stearate. In some other
embodiments, the charge director is zirconium(IV) octoate or
2-ethyl hexanoate. In yet some other embodiments, the charge
director is zirconium(IV) 2-ethyl hexanoate.
[0040] In some other embodiments, the charge director includes
polyisobutylene succinimide polyamine polymers. An exemplary
embodiment of such charge director includes OLOA.RTM.1200
(available from Chevron Oronite).
[0041] In some examples, the charge director is present in an
amount representing from about 0.001 to about 5 weight percent (wt
%) of the total amount of solids present in the ink composition,
i.e. wt % of total weight of non volatile substances (NVS). In some
other examples, the charge director is present in an amount
representing from about 0.01 to about 0. 5 wt % of the total amount
of solids present in the ink composition.
[0042] In some embodiments, the positively charged ink includes a
liquid carrier. In some examples, the liquid carrier is a nonpolar
liquid carrier. As an example, the liquid carrier has a resistivity
in excess of about 109 ohm-cm and a dielectric constant below about
3.0. In some embodiments, the liquid carriers are hydrocarbons. In
some other embodiments, the liquid carriers are aliphatic
hydrocarbons. In some other embodiments, the liquid carriers are
isomerized aliphatic hydrocarbons. As examples, the liquid carrier
can include, but is not limited to, hydrocarbons, halogenated
hydrocarbons, cyclic hydrocarbons, functionalized hydrocarbons
(where functionalized can include alcohols, acids, esters, ethers,
sulfonic acids, sulfonic acid esters, and the like). The
hydrocarbon can include, but is not limited to, an aliphatic
hydrocarbon, an isomerized aliphatic hydrocarbon, branched chain
aliphatic hydrocarbons, aromatic hydrocarbons, and combinations
thereof. In some embodiments, the carrier liquids include, but are
not limited to, aliphatic hydrocarbon, isoparaffinic compounds,
paraffinic compounds, dearomatized hydrocarbon compounds, and the
like.
[0043] As examples, the carrier liquids can include, but are not
limited to, Isopar-G.RTM., Isopar-H.RTM., Isopar-L.RTM.,
Isopar-M.RTM., Isopar-K.RTM., Isopar-V.RTM., Norpar 12.RTM., Norpar
13.RTM., Norpar 15.RTM., Exxol D40.RTM., Exxol D80.RTM., Exxol
D100.RTM., Exxol D130.RTM., and Exxol D140.RTM. (available from
Exxon corporation); Teclen N-16.RTM., Teclen N-20.RTM., Teclen
N-22.RTM., Nisseki Naphthesol L.RTM., Nisseki Naphthesol M.RTM.,
Nisseki Naphthesol H.RTM., Solvent L.RTM., Solvent M.RTM., Solvent
H.RTM., Nisseki Isosol 300.RTM., Nisseki Isosol 400.RTM.,
AF-4.RTM., AF-5.RTM., AF-6.RTM. and AF-7.RTM. (available from
Nippon Oil Corp.); IP Solvent 1620.RTM. and IP Solvent 2028.RTM.
(available from Idemitsu Petrochemical Corp.); Amsco OMS.RTM. and
Amsco 460.RTM. (available from American Mineral Spirits Corp.); and
electron, positron, new II, PurogenHF.RTM. (100% synthetic
terpenes) (available from Ecolink).
[0044] In some embodiments, the carrier liquids is present in an
amount representing from about 15 to about 99 weight percent by
total weight of the ink composition.
[0045] In some examples, the positively charged ink according to
the present disclosure contains a resin that is a vinyl
pyrrolidone/triacontene copolymer and contains, as charge adjuvant,
2-(4-chlorophenyl)-3-methylbutyric acid. In some other examples,
the positively charged ink contains vinyl pyrrolidone/triacontene
copolymer as resins, 2-(4-chlorophenyl)-3-methylbutyric acid as
charge adjuvant and contains zirconium 2-ethyl hexanoate as charge
director.
[0046] In some examples, the ink composition can contain other
components, such as for example, dispersing agents. In some
embodiments, the dispersing agents or other components represent
from about 0.05 wt % to about 60 wt % of the total weight of non
volatile substances. In other embodiments, the dispersing agents or
other components represent from about 0.5 wt % to about 25 wt % of
total weight of non volatile substances present in the ink
composition.
[0047] The ink compositions are to be charged in accordance with
embodiments of the present disclosure and may be prepared using any
of various methods known in the art. Exemplary embodiments of
method of making an positively charged ink, include: firstly,
grinding a carrier liquid, a basic resin and a pigment, to form an
ink slurry; then, mixing an acidic charge adjuvant and a charge
director with the ink slurry after grinding; and, ultimately,
forming the ink.
[0048] An exemplary method of making the positively charged ink
according to the present disclosure includes: grinding a carrier
liquid, a vinyl pyrrolidone/triacontene copolymer resin and a
pigment, to form a slurry; mixing a charge adjuvant and a charge
director with the slurry after grinding, wherein the charge
adjuvant is 2-(4-chlorophenyl)-3-methylbutyric acid or
4-(2,4-dichlorophenoxy)butyric acid; and forming the ink.
[0049] In some example, when the charge adjuvant is not dissolved
in the carrier liquid, the charge adjuvant is added during the
gridding.
[0050] In some examples, the carrier liquid, the resin, and the
pigment are mixed in a mixer (e.g., double planetary mixer and the
like). Other components such as, but not limited to, charge
adjuvants, organic/inorganic pigments, surface modifiers, and
additives, can be added to the slurry at this stage and/or during
the next stage. Next, the slurry is added to a grinder (e.g., an
attritor, a disk mill, a sand mill, an impeller attrition mill, a
vibro-energy mill, or the like), and ground for a period to form
the ink composition.
[0051] In some other examples, the charge adjuvant can be added
after the grinding of the components in the ink toner (e.g., the
carrier liquid, the resin, and the like). Addition of the charge
adjuvant after grinding allows the user to tune the electrical and
physical characteristics of the ink composition. The
characteristics that can be tuned include, but are not limited to,
viscosity, low field conductivity, high field conductivity, dc
conductivity, particle conductivity, total charge and mobility, and
combinations thereof. For example, the viscosity of the ink can be
chemically modified (e.g., decreased) by changing the amount of
charge adjuvant homogeneously added to the ink composition. As
mentioned above, the charge adjuvant can be added to the mixture
prior to grinding or after grinding. In addition, the charge
adjuvant can be added before, after, or at the same time as the
charge director. More precisely, in an example, a basic resin
polymer, such as, Antaron.RTM.WP-660 wax resin (available from
International Specialty Products), is mixed with a carrier liquid,
as for example Solvent L.RTM. (manufactured by Idemitsu
Petrochemical Corp), at elevated temperature (e.g. 120.degree. C.
to 130.degree. C.) to form a slurry of the carrier liquid and
polymer toner particles plasticized with the carrier liquid. The
slurry is allowed to cool while mixing and carrier liquid is
generally added to dilute the slurry so that it includes, for
example, between 10 to 23% by weight of solids. While cooling, the
slurry is precipitated in a form of paste. Pigments are added to
provide the particles with a desired color and the mixture is
loaded into a ball mill and grounded, starting at a temperature of
about 60.degree. C. and being reduced to room temperature,
generally for about 20 hours, until the toner particles have a
desired size distribution and are appropriately percolated by the
pigment. In some examples, the charge adjuvant is added to the
toner during grinding. In some other examples, the charge adjuvant
is not added during grinding but is added after the toner has been
produced and already contains the charge director. In some
embodiments, the charge adjuvant is
2-(4-chlorophenyl)-3-methylbutyric acid.
[0052] Following grinding, the liquid composition is allowed to
cool to at room temperature, and a charge director is added and
mixed to percolate the charge director through the toner. In some
examples, the charge director includes OLOA.RTM.1200. The
composition is then left to sit for a sufficient period for the
charge director to charge the particles. In some examples, the
resulting composition contains a concentration of non-volatile
solids comprised between 2 and 45 wt % and is diluted with
additional quantities of carrier liquid as may be needed for
storage or printing. For storage, the composition may be diluted to
about 20% by weight of non-volatile solids (NVS). In some examples,
immediately prior to use, the concentrate is may be diluted with
additional carrier liquid to a concentration of about 0.1% to about
7% by weight of NVS.
[0053] In some embodiments, the ink composition has weight
percentage of non-volatile substances that is between about 1% and
about 45% of total weight of ink composition. In some other
embodiments, the ink composition has weight percentage of
non-volatile substances that is between about 5% and about 25% of
total weight of ink composition. In some embodiments, the ink toner
has a viscosity of about 1 to 1000 cps, depending of ink particle
morphology, additive concentration, the percentage of
non-volatile-substances (NVS), and other options. The viscosity of
the ink toner can be modified by changing the concentration of the
charge adjuvant added to the ink toner. The viscosity change takes
place while maintaining the original ink morphology. This can be
provided fixing qualities, usually obtainable, from higher
viscosity inks to low viscosity inks In some examples, the ink
composition has a viscosity which is below 50.0 cps, when measured
at 25.degree. C., and has, at least, 10 wt % of total weight of ink
composition of non volatile substances (NVS).
[0054] As used herein, the percentage of non-volatile substances (%
NVS) represents the percentage of solid ingredient present in the
formulation. In other word, it represents the total amount of solid
ingredients and/or components that remain in the composition once
the volatile substance is evaporated, in this specific case when
the carrier liquid is evaporated. In some examples, the
non-volatile substances (NVS) include the pigment-loaded, resin
particles, the charge adjuvant and the charge director.
[0055] In some embodiments, the ink composition has a low field
conductivity of about 0.1 to 300 or about 1 to 100 pmho/cm (or
pS/cm). The low field conductivity of the ink composition can be
modified by changing the concentration of the charge adjuvant added
to the ink. In some other embodiments, the ink composition has a
high field conductivity of about 10 to 500 pmho/cm (or pS/cm). The
high field conductivity of the ink composition can be modified by
changing the concentration of the charge adjuvant added to the ink
or/and the charge director concentration.
[0056] In some embodiments, the ink composition can also contain
others additives such as a surface modifier, compatibility
additives, a viscosity control agent media additives, fixing
additives and other additives. In yet some embodiments, a viscosity
control agent assists in maintaining viscosity of starting
materials combined in a resin grinding and pigment dispersion
process to adequately reduce particle size. During the processing,
depending on physical properties of the resin and pigment and the
operating conditions for grinding, pigment may become encapsulated
by resin when loading it on the resin, though encapsulation is not
required. A viscosity control agent may be selected that, after
grinding, functions as a charge adjuvant.
[0057] The inks disclosed herein are suitable for use in a variety
of applications, including display applications, electronic skins,
blanket jetting applications, digital printing applications,
ion-beam printing applications, or other printing applications. The
positive charging of the ink provides the possibility to develop a
positive electrophoretic image in current press mode and is also
well adapted for use in a dual color development display as well as
in ion beam development technique.
[0058] In some examples, the ink of the present disclosure is used
as a positively charged liquid toner in electrophotographic
printing process. In such printing process, a digital printer forms
a latent image on a photosensitive imaging plate that is then
developed by applying the ink of the present disclosure to said
photosensitive surface. The ink composition can then be transferred
from the photosensitive imaging plate to an intermediate transfer
member. In an ultimate step, the ink toner of the present
disclosure is transferred to the substrate in view of printing the
desired image. As another example, the ink composition is used in a
method of forming printed image on supporting substrates. More
precisely, as another example, the ink composition of the present
disclosure is used in a method for developing electrostatic latent
image. Such method includes forming an electrostatic latent image
on a photo-responsive device, contacting the resulting image with
the ink composition of the present disclosure and transferring the
image to a suitable substrate, and permanently fixing the image
thereto.
[0059] In some examples, the ink of the present disclosure is used
as electronic inks In some other examples, the ink is used as
positively charged electronic inks for display applications such as
e-skin and/or e-paper. The positively charged electronic ink is
applicable for dual color (binary charged) displaying applications
towards full color e-paper. Among the wide variety of known
electronic displays, some involve electronically controlling the
location of charged particles suspended in a fluid. Electrophoretic
displays represent one type of electronic display and involve
moving the charged particles suspended in the fluid with a
Coulombic force exerted on the particles by an applied electrical
signal. Some electronic displays are referred to as electronic
paper or e-paper, since they can be thin and flexible with
paper-like image quality. Electronic displays may use transmitted
light, but some use only reflected light. As an example, electronic
inks include charged particles, such as colorant particles, in
order to help particles to respond to an electric field and to
rearrange within the viewing area of the display to produce desired
images. In some examples, the inks disclosed herein have relatively
high zeta potentials (i.e., greater than or equal to +20 mV), and
thus are particularly suitable for electronic display applications
(such as, for example, electro-optical displays). Such
electro-optical displays include those that are driven by
electrophoresis and/or electro-convective flow.
[0060] In some embodiments, the ink of the present disclosure is
used as electronic ink in a pixel of an electronic display. As an
example, the electronic display includes a pixel, an electrode in
the pixel, and electronic ink in the pixel wherein the ink contains
charged particles that include a combination of carrier liquid, a
basic pigment-loaded resin particle, a charge director and an
acidic charge adjuvant.
[0061] In some examples, the average particle size of the basic
pigment-loaded resin particles of the ink contained in the pixel is
less than 2.0 micrometer; in some other examples, less than 1.0
micrometer. A dispersing agent may be provided, enhancing particle
mobility. Various types and configurations of electrodes known to
those of ordinary skill may be used, including bare electrodes
contacting the ink and/or electrodes coated so as not to contact
the ink.
[0062] In other embodiments, an image displaying method includes
providing an electronic display including a pixel allowing visible
light to enter and exit the pixel, an electrode in the pixel, and
electronic ink in the pixel wherein the ink contains charged
particles that include a combination of carrier liquid, a basic
pigment-loaded resin particles, a charge director and an acidic
charge adjuvant. The method includes applying an electrical signal
to the pixel using the electrode and compacting the charged
particles using the electrical signal. The electrical signal is
changed and the charged particles are dispersed across the pixel.
By way of examples, the method may include repeatedly compacting
and dispersing during at least 10 signal application cycles without
substantial degradation of the charged particles. Practically, the
cycling may occur millions of times in an electronic display. In
some other examples, the inks of the present disclosure can also be
used in displays with in-plane shutter architectures, where the
colorant particles are moved laterally into and out of a field of
view in a pixel or sub-pixel display cell. Embodiments of the
electronic inks are particularly suitable for this type of display,
which tends to produce brighter and more colorful images than other
displays.
[0063] The following examples illustrate the embodiments of the
disclosure that are presently best known. However, it is to be
understood that the following are only exemplary or illustrative of
the application of the principles of the present invention.
Numerous modifications and alternative compositions, methods, and
systems may be devised by those skilled in the art without
departing from the spirit and scope of the present invention. The
claims are intended to cover such modifications and arrangements.
Thus, while the present invention has been described above with
particularity, the following examples provide further details in
connection with what are presently deemed to be the most practical
and preferred embodiments of the disclosure.
EXAMPLE 1
[0064] Procedure for making the ink
[0065] Sample 1: Antaron.RTM.WP-660 wax resin is used.
Antaron.RTM.WP-660 (WP-660) wax resin has a molecular weight of
3,000 to 4,500 and a melting point of 58-68.degree. C. The WP-660
resin is put in a batch grinding mill along with: CL2 as charge
adjuvant, Yellow pigments (Paliotol.RTM. yellow D1155) and
Solvent-L.RTM. as liquid carrier. The mixture is grinded in an S0
attritor (from Union process) for 20 hours at 250 rpm. The
formulation in the mill contains 51 parts of resin, 4 parts of
charge adjuvant and 45 parts of pigment, on a solid weight basis,
in enough Solvent-L.RTM. to provide 18 wt % NVS during grinding.
Pigment loading is of 45 wt %. After grinding for at least 6 hours
at 35.degree. C., the resulting dispersion exhibit a particle size
distribution with an average of 0.7 .mu.m and a maximum of 1.2
.mu.m as determined using a Mastersizer.RTM. 2000 particle
analyzer.
[0066] Sample 2: The same method as described in sample 1 is
followed except that formulation in the mill does not contain
charge adjuvant. The ink formulation contains thus 55 parts of wax
resin Antaron.RTM.WP-660 (WP-660) and 45 parts of yellow pigment.
The pigment loading is 45 wt %. A scanning electron microscope
(SEM) photo shows a block structure for the particles and an
average particle size of 0.75 .mu.m (and a cutoff of 1.2
.mu.m).
[0067] Sample 3: The same method as described in sample 1 is
followed except that the ink formulation contains CL1 as charge
adjuvant. The formulation in the mill contains thus 51 parts of wax
resin Antaron.RTM.WP-660 (WP-660), 4 parts of charge adjuvant CL1
and 45 parts of pigment, on a solid weight basis, in enough
Solvent-L.RTM. to provide 18 wt % NVS during grinding.
[0068] Sample 4: The same method as described in sample 1 is
followed except that the ink formulation contains AC-575
(Alcyn.RTM.575) wax resin instead of WP-660 resin. Alcyn.RTM.575
(AC-575) resin exhibits a molecular weight of 1,000 to 3,000, a
melting point of 106.degree. C. by Mettler drop technique (ASTM
D-3954), and a saponification number of 34 mg KOH/g. The
formulation in the mill contains thus 51 parts of wax resin, 4
parts of charge adjuvant CL2 and 45 parts of pigment, on a solid
weight basis, in enough Solvent-L.RTM. to provide 18 wt % NVS
during grinding.
[0069] Sample 5: The same method as described in sample 4 is
followed except that ink formulation contains CL1 as charge
adjuvant. The formulation in the mill contains thus 51 parts of wax
resin AC-575, 4 parts of charge adjuvant CL1 and 45 parts of
pigment, on a solid weight basis, in enough Sol-L to provide 18 wt
% NVS during grinding.
[0070] Formulations and ratio of samples 1 to 5 are illustrated in
TABLE (a) below.
TABLE-US-00001 TABLE (a) Samples 1 2 3 4 5 Resin 51% WP-660 55%
WP-660 51% WP-660 51% AC-575 51% AC-575 Pigment 45% Yellow 45%
Yellow 45% Yellow 45% Yellow 45% Yellow Charge adjuvant 4% CL2 --
4% CL1 4% CL2 4% CL1 Carrier liquid Sol-L Sol-L Sol-L Sol-L Sol-L
Pigment loading (%) 45 45 45 45 45 Percentage NVS 18% 18% 18% 18%
18% average particle size 0.7 0.75 0.65 0.66 0.65 maximum size
(.mu.m) 1.2 1.2 1.2 1.7 1.5
[0071] Charging and conductivity data
[0072] For each of the exemplary ink samples 1 to 5, 100 mg/g
solids of charge director (OLOA.RTM.1200) is added. The resulting
compositions are mixed in a shaker to yield initial low field
conductivity of 80 pS (as measured in a Q/m test cell). The inks
are then allowed to sit for a charging period (12 hours) during
which charges accumulate on ink particles and are stabilized. The
inks are subsequently diluted with Solvent-L.RTM. to a Non Volatile
Solvent (NVS) concentrate of about 2% w/w. Particles conductivity
(PC) of the diluted sample inks are then evaluated in Q/m test
cells. The particle's conductivity is expressed in pS (1 pS/cm=1
pmho/cm). The results are illustrated in TABLE (b) below and in
FIG. 1. FIG. 1 is a graph representation of the measured particle
conductivities (PC in pS) for ink compositions 1 to 5 (comprising
CL1, CL2 or without any charge adjuvant and comprising AC-575 or
WP660 resins), charged with OLOA.RTM.1200.
TABLE-US-00002 TABLE (b) Samples 1 2 3 4 5 Conductivity (in pS/cm)
27 3 0 -9 -5
EXAMPLE 2
[0073] Ink samples A to H are prepared as described in example 1.
Different resins and charge adjuvants are used. TABLE (c) reflects
the different ink formulations of samples A to H.
TABLE-US-00003 TABLE (c) Samples A B C D E F G H Resin 55% 55% 51%
51% 51% 51% 51% Resin VCA WP-660 AC-575 WP-660 AC-575 WP-660 AC-575
WP-660 Pigment 45% 45% 45% 45% 45% 45% 45% 45% Yellow Yellow Yellow
Yellow Yellow Yellow Yellow Yellow Charge -- -- 4% CL1 4% CL1 4%
CL2 4% CL2 4% stearate/ adjuvant ZZ11 palmitate Carrier Sol-L Sol-L
Sol-L Sol-L Sol-L Sol-L Sol-L Sol-L liquid Percentage 18% 18% 18%
18% 18% 18% 18% 18% NVS (%)
[0074] For each of the exemplary ink samples (A to H), a solution
of 10 w/w % of charge director ZZ11 (Zirconium 2-ethyl hexanoate)
is added. The resulting compositions are mixed in a shaker to yield
initial low field conductivity of 80 pS in the Q/m test cell. The
inks are then allowed to sit for a charging period (12 hours)
during which charges accumulate on the ink particles. The inks are
subsequently diluted with Isopar-L.RTM. to a Non Volatile Solvent
concentrate of about 2 w/w %. A 2% NVS dispersion of each of the
ink samples are charged with the above charge director solution by
100 mg/g level. Particles conductivity (PC) of the diluted samples
is evaluated in the Q/m test cell. The high field conductivity is
measured in Q/M cell while the low field conductivity is measured
in a Z-electrodes stick meter device. The particle's conductivity
is expressed in pS. LFC is Low Field Conductivity. HFC is high
field conductivity. DC is direct conductivity and denotes residual
direct conductivity. PC (particles charge) is defined as the
difference between high field and low field conductivities.
[0075] The results of the particle conductivity, charged with ZZ11,
are illustrated in FIG. 2 and in TABLE (d). FIG. 2 shows a graph
representing the measured particle conductivities (PC) for ink
compositions A to H charged with ZZ11.
TABLE-US-00004 TABLE (d) Item Charging HFC LFC DC PC Sample
Charging system kinetic (h) (pS/cm) (pS/cm) (pS/cm) (pS/cm) A Resin
Resin - WP 660 0 5 0.2 Charge director - ZZ11 48 96 38 46.7 58 B
Resin - Aclyn 575 18 27 0.3 Charge director - ZZ11 48 19 0 0.2 19 C
Charge adjuvant Resin - WP 660 18 162 10 Charge adjuvant - CL1
Charge director - ZZ11 48 139 32 9.9 107 D Resin - Aclyn 575 18 22
0.3 Charge adjuvant - CL1 Charge director - ZZ11 48 6 0 0.2 6 E
Resin - WP 660 0 28.55 0.75 Charge adjuvant -CL2 Charge director -
ZZ11 48 330.7 67 13.5 264 F Resin - Aclyn 575 18 39 0.3 Charge
adjuvant -CL2 Charge director - ZZ11 48 40 0 2.7 40 G Resin - WP
660 0 22 3.2 Charge adjuvant -ZZ11 Charge director - ZZ11 48 139 50
12.15 89 H Resin/charge adjuvant Resin VCA 6 0 0.15 6 Charge
adjuvant- A1 stearate/palmitate Charge director - ZZ11
EXAMPLE 3
[0076] Particle conductivity (PC) and direct conductivity (DC) are
evaluated as a function of the concentration of the charge director
ZZ1 at different kinetic states. The kinetics of this system is
measured in short and long time scale up to 2 weeks. The results
are illustrated in FIGS. 3A and 3B. FIG. 3A shows a graph of the
measured particle conductivities (PC) for the yellow ink
composition E charged with different concentrations of ZZ11, at
different kinetic states. FIG. 3B shows a graph of the measured
Direct current conductivity (dc) for the yellow ink composition E
charged with different concentrations of ZZ11, at different kinetic
states. The conductivity of the particle is dependant of the
concentration of the charging director (ZZ11).
EXAMPLE 4
[0077] The particle conductivity of ink formulations E1, E2 and E3,
containing different amounts of charge adjuvant CL2 as illustrated
in TABLE (e) below, are tested. The results are illustrated in FIG.
4. FIG. 4 shows a graph of the measured particle conductivities
(PC) for ink compositions E1, E2 and E3, as function of the charge
adjuvant (ZZ11) concentration (ranging from 0 to about 150 mg/gram
24 h after charging). The result demonstrates that charge adjuvant
concentration has an effect on the conductivity.
TABLE-US-00005 TABLE (e) Samples E1 E2 E3 Resin WP-660 51% 51% 46%
Yellow Pigment 45% 45% 45% Charge adjuvant CL2 0% 4% 8%
EXAMPLE 5
[0078] The particles conductivities of ink formula E are tested
with formulation containing different amounts of
Solsperse.RTM.11200. The results are illustrated in FIG. 5. FIG. 5
shows a graph of the measured conductivities (PC, HFC, LFC, Dc and
PC) for ink composition E (charged with ZZ11, at 100 mg/g) for
different concentrations of dispersant (2.5, 5 and 10 mg/g of
Solsperse.RTM.11200). Measurements are made during 24 hours. The
results demonstrate that addition of dispersants does not influence
significantly conductivities of ink compositions.
EXAMPLE 6
[0079] Antaron.RTM.WP-660 wax resin is put in an S-0 Attritor (made
by Union Process) batch grinding mill along with CL2, black and
blue pigments (Mon-800.RTM. and Reflex.RTM.blue-d6200) and
Solvent-L.RTM.. The formulation contains 51 parts of wax resin, 4
parts of charge adjuvant and 45 parts of pigment, on a solid weight
basis, in enough Solvent-L.RTM. to provide 18 wt % NVS during
grinding. Pigment loading is 45 wt %. The grinding is carried
overnight at 35.degree. C. The charging of the resulting ink is
done with ZZ11 (Zirconium 2-ethyl hexanoate) at a level of 100 mg/g
(as to solid content) and its kinetic is recorded for the next 48
hours. The results are illustrated in FIG. 6. FIG. 6 shows a graph
of the measured conductivities (PC, HFC, LFC, Dc and PC) for ink
composition containing black and blue pigments (charged with ZZ11
100 mg/g) during 48 hours.
[0080] Definition of Ingredients Used in the Examples [0081]
Antaron.RTM.WP-660 (WP 660) is a resin available from International
Specialty Products. [0082] Alcyn.RTM.575 wax (AC-575) is a resin
available from Honeywell Inc. [0083] Resin VCA is Nucrel-960.RTM.,
a polyethylene methacrylic acid copolymer from DuPont. [0084]
Paliotol.RTM. yellow D1155 is a pigment available from BASF Corp.
[0085] CL1 is 4-(2,4-dichlorophenoxy)butyric acid, available from
Sigma Aldrich. [0086] CL2 is 2-(4-chlorophenyl)-3-methylbutyric
acid, available from Sigma Aldrich. [0087] ZZ11 is zirconium(IV)
2-ethyl hexanoate available from Alfa Aesar. [0088] OLOA.RTM.1200
is polyisobutylene succinimide polyamine, available from Chevron
Oronite. [0089] Isopar-L.RTM. is a carrier liquid available from
Exxon Corporation. [0090] Solvent-L.RTM. (Sol-L) is a liquid
carrier available from Idemitsu Petrochemical Corp. [0091]
Stearate/palmitate is charge adjuvant (aluminum di/tri
stearate/palmitate salt). [0092] Mon-800.RTM. is a pigment
available from Cabot-BASF. [0093] Reflex.RTM.blue-d6200 is a
pigment available from BASF. [0094] Solsperse.RTM.11200 is a
dispersant available from Lubrizol.
[0095] The preceding description has been presented only to
illustrate and describe exemplary embodiments of the present
disclosure. Although certain example compositions, methods and
apparatus have been described herein, the scope of coverage of this
patent is not limited thereto. On the contrary, this patent covers
all compositions, methods and apparatus fairly falling within the
scope of the claims either literally or under the doctrine of
equivalents.
* * * * *